1. Field of the Invention
The present invention relates to an apparatus for transferring sheet material of the type including guiding means of which a guiding surface is spaced away from the circumferential surface of a rotational transferring member and pressing means for pressing the sheet material against the rotational transferring member so that transferring is achieved in such a manner that the sheet material is wound about the rotational transferring member.
2. Related Background Art
Generally, a conventional recording apparatus such as printer or the like is so constructed that recording is effected while a sheet of recording medium (hereinafter referred to as recording sheet or sheet) is transferred and in most of the conventional recording apparatuses transferring of the recording sheet is achieved in accordance with the so-called friction feed system in which pinch rollers are brought into pressure contact with the rotational transferring roller and the recording sheet is transferred along the circumferential surface of the transferring roller while it is held between both rollers.
When it becomes necessary that the recording sheet assumes a correct position or orientation prior to starting the transferring operation in the above-mentioned type of transferring apparatus in which the pinch rollers are brought into pressure contact with the pinch roller or when transferring is achieved in accordance with the so-called pin tractor feed system in which the transferring roller is provided with a plurality of pins which are projected from the circumferential surface thereof and onto which small holes on both the end parts of the recording sheet are fitted during the transferring operation, there is a necessity for releasing the transferring roller and the pinch rollers for the pressure contact state.
Accordingly, it has been pointed out as problems inherent to the conventional sheet transferring apparatus adapted to be operated in accordance with the friction feed system that the apparatus is provided with specially designed pressure contact releasing members, actuating lever shafts or like means in order to assure that the pinch rollers are displaced away from the transferring roller, resulting in an increased number of components and increased manufacturing cost of the apparatus.
Especially, in the case where the apparatus is equipped with a number of pinch rollers which are arranged in plural lines, it is unavoidable that the structure of the apparatus becomes complicated.
Generally, the conventional recording apparatus such as a printer or the like is so constructed that recording is effected while a recording sheet is transferred along the circumferential surface of the transferring roller. However, when the sheet is floated up above the circumferential surface of the transferring roller during recording operation, it results that normal recording cannot be achieved as required. To inhibit an occurrence of floating-up in that way, arrangement is made for the conventional recording apparatus such that a sheet retainer made of a resilient thin plate is caused to come into pressure contact with the transferring roller. Thus, the sheet retainer inhibits the recording sheet from floating up above the circumferential surface of the transferring roller.
To assure that an occurrence of floating-up is inhibited without fail even when a firm recording sheet such as thick paper or like material is used, it is necessary that the sheet retainer is brought into pressure contact with the transferring roller with a sufficiently high intensity of pressure contact force.
However, when it is required that a recording sheet assumes a correct position or orientation or when transferring is effected in accordance with the so-called pin tractor feed system in which the transferring roller is provided with a number of pins which are projected outwardly therefrom and onto which feeding holes on both the end parts of the recording sheet are fitted during transferring operation, it is preferable from the viewpoint of manoeuvrability that the sheet retainer is brought into pressure contact with the transferring roller with a reduced intensity of pressure contact force. When pressure contact force has excessively high intensity, the recording sheet is forcibly pulled under the effect of this pressure contact force. Thus, there is a fear of causing elongation of the feeding holes or breakage of the same.
In view of the fact as mentioned above it has been requested that arrangement is made for the recording apparatus so as to properly adjust the pressure contact force to be imparted by means of the sheet retainer. However, to meet the requirement there is the necessity for additionally attaching a pressure contact force adjusting member to the apparatus, resulting in the increased number of components and increased manufacturing cost of the apparatus. For that reason no countermeasure has been hitherto taken.
Further, to assure that a recording sheet is transferred without fail a conventional recording apparatus is provided with guiding means having a guiding surface which is spaced away from the circumferential surface of the transferring roller. In addition, another guiding means is provided in order to bring to the first-mentioned guiding means the recording sheet which is fed through a sheet insert slit. However, it is found that an interrupted area is produced at the connection parts of both the guiding means when the first-mentioned guiding means is turned along the transferring roller and production of the interrupted area in that way inhibits smooth transference of the recording sheet.